Under-Cover-Integrating-Cover-Crops-into-Silage-Corn-Systems

A Publication of the University of Vermont Extension Northwest Crops and Soils ProgramUnder Cover Integrating Cover Crops into Silage Corn Systems... Under CoverIntegrating Cover Crops i

A Publication of the University of Vermont Extension Northwest Crops and Soils Program

Under Cover

Integrating Cover Crops into Silage Corn Systems

Under Cover

Integrating Cover Crops into

Silage Corn Systems

University of Vermont Extension helps individuals and communities put research-based knowledge

to work

A Publication of the University of Vermont Extension

Northwest Crops & Soils Program

Lead Author:

Dr Heather Darby

Contributing Authors:

Conner Burke Lilian Calderwood Hannah Harwood Debra Heleba Jeffrey Sanders

Editor:

Debra Heleba

Copyright © 2015 by University of Vermont Extension All rights reserved No part of this work may be reproduced without prior permission from the lead author

Published February 2015 by the University of Vermont Extension Northwest Crops and Soils Program.

Acknowledgements:

The authors thank the following individuals for their assistance in providing information for and/or review of the guide: Dr Sid Bosworth, University of Vermont Department of Plant and Soil Science; Dr Bill Curran, Pennsylvania State University; Roger Rainville, Borderview Re-search Farm; and Lindsey Ruhl, University of Vermont Extension

Much of the information included in the guide is based upon work supported in part by the Cooperative State Research, Education, and Extension Service, U.S Department of Agriculture, under Agreement No 2008-51130-19504; Lake Champlain Sea Grant; Northeast Extension Risk Management Education Center supported by USDA/NIFA under Award Number 2012-49200-20031; and Organic Valley’s Farmers Advocating for Organics (FAFO) Fund

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in operation with the United States Department of Agriculture University of Vermont Extension, Burlington, Vermont University of Vermont Extension, and U.S Department of Agriculture, cooperating, offer education and employment to everyone without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or famil-ial status

co-Every effort has been made to make this publication as complete and accurate as possible The text is only a guide, however, and should be used in conjunction with other information sources

on crop, soil, and farm management The authors, editor, and publisher disclaim any liability, loss, or risk, personal or otherwise, that may be incurred as a consequence, directly or indirectly,

of the use and application of any of the contents of this publication

Any reference to commercial products, trade names, or brand names is for information only, and no endorsement or approval is intended

Introduction 1

Soil Health 2

Costs & Benefits 4

What to Grow 7

Grasses 7

Legumes 9

Brassicas 9

Cover Crop Cocktails 11

Establishment 12

Planting Just Prior to Canopy Closure 12

Seeding Prior to Corn Harvest 14

Planting Post-Harvest 15

Seeding Rates 19

Herbicide Impact on Establishment 21

Cover Crop Termination 23

Winter Kill 23

Plow Down 23

Herbicide 24

Harvest 24

Rolling 25

Final Thoughts 26

Resources 26

I

ntegrating cover crops into field crop production has gained interest in recent years as we discover the mul-titude of benefits that cover crops can provide to cash crops like corn For example, cover crops can reduce nutrient and soil loss, increase soil organic matter, suppress weeds, and even serve as extra sources of live-stock forage All of these benefits help translate into increased cash crop productivity In general, the benefits from cover cropping far outweigh the costs of implementation, but to use them with success, you need to identify your goals for using covers as well as potential farm and field constraints Various cover crop species can provide differ-ent benefits but each comes with their own unique advantages and disadvantages

Successfully incorporating cover crops into your silage corn production will take advanced planning to realize the benefits these crops can offer Figure 1 is an example of an annual cropping system that integrates cover

crops Note that timely planting and termination are both critical to the success of any cover crop.

This guide covers a variety of agronomic strategies that will help you build a silage corn system that integrates cover crops These include variety selection, planting dates, seeding rates, and termination strategies Much of the information in the guide is based on research conducted by the University of Vermont (UVM) Extension Northwest Crops and Soils Program (NWCS) Since 2003, our NWCS team has been conducting on-farm trials throughout Vermont, including several to evaluate cover cropping practices in corn silage systems You can find

a link to our research reports as well as additional cover crop resources at the end of the guide

Harvest corn.

chase corn seed & fertilizer.

Pre-pur-Obtain seed blends for cover crop plan.

Spread manure / soil test.

Fall ing of cover crop.

Design cover crop plan.

Assess stand planted last year.

Spread manure on 6-8” estab- lished cover crop Manure injection also works well.

figure 1 Example of 12-month cover cropping schedule.

Improving soil health is a major benefit to adding a cover crop to your corn rotation Cover crops can positively contribute to both the physical and biological properties of field soils For example, when soil is left exposed through the winter, land is physically at risk to erosion and leaching of nu-trients and herbicides into water sources Soil compaction can accumulate from season to season, reducing the corn’s ability to scavenge for nutrients and obtain oxygen needed for adequate growth and development Cover crops reduce these risks by creating root networks that help build soil struc-ture while breaking up compaction and increasing soil aggregation, facili-tating air and water flow Cover crops are also actively growing and require water and nutrients, hence available water and nutrients can be scavenged

by cover crops in the late and early season One of our research projects conducted in St Albans in Spring 2007 found lower soil moisture levels and higher soil temperatures in cover crop treatments compared to soils without

a cover crop (Figure 2) Here, we learned that corn planted following a erly managed cover crop had a head start in a warmer and drier seedbed

24-Apr 1-May4 -May 7-May

Cover Crop No Cover Crop

46 48 50 52 54 56 58

60 24-Apr 1-May4 -May 7-May

figure 2 Soil moisture and temperatures of heavy clay

plant-ed to cover crop as comparplant-ed to no cover crop.

As mentioned, cover crops can act as nutrient storage For example, in our region, it is a common practice to apply manure to corn acreage in the fall, especially where fall tillage is practiced But plant available nitrogen (N) can be lost from fall manure applications through erosion, leaching, and denitrification If a cover crop is planted, these plants can absorb nutrients and store them in their biomass through the winter Our research has shown that 50% of manure nitrogen was available for corn to scavenge from a fall-planted cover crop, as compared to 15% of manure N available to corn without a cover crop Cover crop biomass can hold high quan-tities of nutrients, especially if the cover crop is able to obtain sufficient growth prior to termination Table 1 shows nutrient levels in soil where cover crops were grown Levels of nutrients were higher in soil with no cover crop indicating that the cover crops were able to scavenge considerable levels of nutrients Nutrients such as phosphorus (P) held by cover crop biomass are less prone to environmental losses Integrating cover crops can also reduce the leaching of potassium (K), ultimately reducing the amount of purchased fertilizers for succes-sive crops.

Cover crop residues increase the microbial or biological activity in the soil as well Research has shown that the soil’s biological activity is very low when bare soil is left following silage corn harvest By growing cover crops, you are helping to feed microorganisms in the soil, including fungi, bacteria, arthro-pods, and protozoa These microorganisms release nutrients bound up in the soil, making them more available to your crop In addition, they interact with plant growth regulation and enhance pest (insect, disease, and weed) defense mechanisms within cash crops

Individual cover crop species perform very specific roles—clover, for example,

fixes nitrogen—but all cover crops help improve soil health in some way.

table 1 Effects of cover cropping on soil health.

K (ppm) (ppmmg ) (ppmCa ) CeC(meq

100 g -1 )

Zn (ppm) organiCSoil

matter (%)Annual ryegrass 7.23 44.3 284 193 3231 18.5 1.33 3.93

Radish 7.10 39.8 253 191 3009 17.3 1.13 4.07

Control (No

cover) 7.20 57.4 322* 219 3175 18.5 1.40 4.30LSD (0.10) 1 NS NS 34 NS NS NS NS NS

Trial Mean 7.18 47.2 286 201 3138 18.1 1.29 4.10

1Least significant difference NS=Difference between treatments was not statistically significant

Tillage radish.

C oStS and b enefitS

When getting started with cover crops, it is a good idea to determine what this practice is going to cost The following spreadsheets provide estimated costs and benefits for establishing cover crops, based on calculations made in 2014 using the USDA Natural Resources Conservation Service (NRCS) Cover Crop Economics Tool at: www.nrcs.usda.gov/wps/portal/nrcs/main/national/technical/econ

The spreadsheets use five examples of typical cover crop scenarios in silage corn as follows:

1 Cereal rye that has been drilled after corn harvest and terminated in the spring by plow down;

2 Annual ryegrass that has been broadcast seeded and terminated by disking;

3 Triticale that has been drilled following corn harvest and harvested for forage in the spring;

4 A cereal rye and radish mix that has been aerially seeded and terminated by herbicide; and

5 A mix of annual ryegrass, clover and radish that has been broadcast seeded at the time of topdress and terminated by herbicide In this scenario, corn is planted using a no-till system

The calculations we’ve provided rely on several built-in formulas and look-up tables included in the NRCS Cover Crop Economic Tool Clearly, these are estimates; for example, per pound seed costs are based on NRCS recommended seeding rates and estimated seed costs per pound in 2014 (see below)

While the actual costs and benefits will vary from farm to farm and from year to year, these estimates should give a general financial picture of what you might expect when implementing cover crops on your farm

NRCS Seeding Rates

(Pounds of Seed) Cereal Rye Ryegrass Annual Triticale Cereal Rye & Radish Mix

Annual grass, Clover

Rye-& Radish Mix

Broadcast 112 30 112 85, 4 18, 6, 4

Cost per pound

(2014 prices) $0.25 $0.60 $0.50 $0.41 $1.86

e xpenSeS (CoStS per aCre)

S Cenario 1 Cereal Rye:

Drilled &

Plowed Down

S Cenario 2 Annual Rye:

Broadcast &

Disked

S Cenario 3 Triticale:

Drilled &

Harvested

S Cenario 4 Cereal Rye &

Radish: ally Applied

Aeri-S Cenario 5 Annual Rye, Radish & Clo- ver: Broadcast

Drilled, Plowed Down

S Cenario 2 Annual Rye:

Broadcast &

Disked

S Cenario 3 Triticale:

Drilled &

Harvested

S Cenario 4 Cereal Rye &

Radish: ally Applied

Aeri-S Cenario 5 Annual Rye, Radish & Clo- ver: Broadcast Nutrient Credits

b enefitS / i nCome (Continued)

S Cenario 1 Cereal Rye:

Drilled, Plowed Down

S Cenario 2 Annual Rye:

Broadcast &

Disked

S Cenario 3 Triticale:

Drilled &

Harvested

S Cenario 4 Cereal Rye &

Radish: ally Applied

Aeri-S Cenario 5 Annual Rye, Radish & Clo- ver: Broadcast Corn Yield

Drilled, Plowed Down

S Cenario 2 Annual Rye:

Broadcast &

Disked

S Cenario 3 Triticale:

Drilled &

Harvested

S Cenario 4 Cereal Rye &

Radish: ally Applied

Aeri-S Cenario 5 Annual Rye, Radish & Clo- ver: Broadcast Total Expenses ($52.14) ($41.69) ($229.76) ($107.99) ($88.42)

Total Benefits /

Income $236.36 $114.36 $419.29 $192.36 $142.93Total Return per

Acre $184.22 $72.67 $189.53 $84.37 $54.51

What to Grow

There are a number of cover crop species you can choose to grow with

your corn silage crops The species and/or mixtures you choose will

depend upon your goals for using them For example, you may be

look-ing to specifically address soil erosion or compaction, fix or scavenge nitrogen,

manage weeds, and/or provide an additional forage source Your choice of cover

crops will also depend upon your planting and termination windows these dates

are naturally dependent on weather conditions but may also be directed by your

farm’s participation in state and federal cost-share programs Table 2 lists some

common cover crop species that have been used in Vermont’s corn silage systems

Triticale very good excellent excellent excellent excellent

Red clover good very good good good excellent

Annual ryegrass very good very good very good very good good

White or alsike

clover fair good very good good excellent

Hairy vetch fair very good good good fair

Forage radish excellent very good very good excellent good

Adapted from “Managing Cover Crops Profitably”

The most common cover crops are those in the grass family Popular covers for silage corn include: a) cereal grains like winter rye, oats, triticale, wheat, and barley; and b) bunch grasses like annual ryegrass In general, these grasses are easier to fit into a corn silage production system than other cover crops They tend to germi-nate quickly and can produce significant biomass under a diverse set of growing conditions Therefore, these covers can be great for erosion control, adding organic matter to the soil, suppressing weeds, and to scavenge nitrogen and store it for the next crop In addition, some of these crops are often thought of as dual purpose, as they can be used as a cover as well as a forage crop

Winter rye seed.

Of all the cover crops used in silage corn plantings, winter or cereal rye (Secale cereale) has been the most

pop-ular in our region Winter rye is a hearty cereal grain that does well in cool climates This annual is considered

a “workhorse” and, although it is not the highest quality forage crop, it is often chosen for its proven reliability and versatility

Winter rye thrives on well-drained, loamy soils but it also performs adequately in heavy clays as well as

droughty, sandy soils It can grow in low-fertility soils; it prefers a soil pH of 5.0 to 7.0, but can tolerate soil pH ranges from 4.5 to 8.0

Winter rye establishes and grows at cooler temperatures so it can be planted later than most other cover crops and still performs well It is the most winter-hardy of all cereal grains, tolerating temperatures as low as -30°F once it is well established It can germinate and grow (with limited vigor) at temperatures as low as 33°F

Compared to other cereal grains, winter rye grows faster in the fall, providing quick cover to otherwise bare soils It persists well, even during severe winters Once spring arrives, it breaks dormancy before other cereal grains and quickly begins to produce biomass Its quick growth in the spring can catch farmers off guard! If not managed properly, excessive amounts of this cover crop’s spring residue may actually delay cash crop planting

or impede its growth and development The decomposing winter rye may “tie up” nitrogen and delay its ability to the silage corn crop Therefore, termination strategies should be carefully considered and planned (see page 23)

avail-Winter rye in silage corn field.

l egumeS

Legumes like perennial clovers (red and white), annual clovers (crimson

and berseem), field peas, and hairy vetch are typically used as cover crops

for their “nitrogen fixing” value Special soil bacteria—Rhizobium spp.—

establish within the roots of legumes; through this symbiotic relationship,

rhizobia are able to draw nitrogen from the air and store it in nodules

within the plant’s root system As the legume plant decomposes, nitrogen

is released, making it available to other plants as a fertility source As

cover crops, legumes are generally slower than other species to establish

and so they are often included as a mixture with other types of covers

Since most are perennials, they do tend to survive the winter; therefore,

proper termination strategies in the spring should be well planned

Another species of cover crop used in silage corn is the brassica Brassicas include radish, turnip, canola seed), and mustard The most popular brassica cover crop is the tillage radish This cover crop is typically used to improve soil structure with their hearty taproots which can alleviate soil compaction and improve soil aeration In addition, because they produce a canopy quickly and provide substantial cover, brassicas can help reduce erosion Our research conducted in Fall 2014 indicates that brassica can be successfully established in our region in mid-August through mid-September and still have adequate growth into the late fall

(rape-Some brassicas, like mustard, contain glucosinolates, naturally occurring compounds that provide soil gant properties to combat soil-borne diseases and other pests However, care needs to be taken to avoid con-tamination in feedstocks as plants like mustard can be toxic to livestock at high concentrations

biofumi-On the other hand, brassicas including kale, turnip, and rape are common as grazed forages These crops are interseeded in late summer for late fall grazing Because the forage quality of the brassica is so high in terms of digestibility and crude protein, care needs to be taken to avoid overfeeding (the feed value is often compared to

a concentrate)

Nitrogen-fixing nodules on Austrian winter pea.

Tillage radish planted at four planting dates at the Borderview Research Farm in Alburgh, harvested November 12, 2014.

e xamples of c over c rops u sed in v ermont s ilage c orn a creages

* Winter kills.